This invention relates to an air filer/oil separator assembly used with internal combustion engines to treat an air-oil mixture taken from an engine crankcase breather and, more particularly, to an air filter/oil separator assembly comprising one or more serviceable oil-coalescing filters.
Air filter/oil separator devices used with internal combustion engines to treat air-oil mixtures taken from an engine crankcase are known in the art. Such devices take an air-oil mixture from the engine crankcase, using a vacuum produced by the intake system of the engine or turbocharger, and separate the oil component from the mixture by passing the air-oil mixture through the device. The separated oil is collected within the device and is routed back to the engine where it is recombined with the engine oil. The air component of the air-oil mixture is passed, via the device, into an intake system of the engine or turbocharger for subsequent combustion. Such devices are described in U.S. Pat. Nos. 5,140,957; 5,479,907; and 6,009,846, which are each incorporated herein by reference.
In order to efficiently remove the oil component from the entering engine crankcase air-oil mixture, such known air filter/oil separator devices typically comprise one or more baffles disposed within an airflow passageway of the device to both reduce the velocity of the air-oil mixture passing through the device, thereby increasing the residence time of the mixture within the device, increasing the thermal contact area between the entering air-oil mixture and the device and, thereby increasing the thermal conduction cooling of air-oil mixture as it is passed through the device. Both of these functions serve to promote the separation of oil from the air-oil mixture, thereby promoting efficient operation of the separator device.
Such separators are known to additionally make use of a permanent filter media within the airflow passageway for purposes of promoting oil coalescing and/or trapping air-borne particles within the device. The filter media can be in the form of one or more filter pads that are placed within internal airflow channels or passageways in the device. In all cases, the filter media is a permanent element within the device and is not serviceable. As a result, while use of the filter element can initially improve operational efficiency of the separator, by promoting oil separation, the service life of an air filter/oil separator device comprising such filter media is somewhat limited to the period of time during which the filter media remains functional. Once the filter media becomes saturated with oil and air-borne particles to the point that a desired pressure differential across the filter media can no longer be maintained, the entire air filter/oil separator device must be replaced.
Such nonserviceable separator devices, therefore, provide a degree of oil removal efficiency that is tempered or compromised by the need to provide a device having an acceptable service life. While one can increase the oil removal efficiency by simply using more baffles or a less restrictive filter media, the service life of the device would be reduced due to higher oil particle and air-borne particle trapping, ultimately causing the device to clog.
It is, therefore, desirable that an air filter/oil separator assembly be constructed in a manner that is both capable of providing an improved oil removal efficiency without compromising separator service life when compared to the conventional air filter/oil separator devices described above.
An air filter/oil separator assembly, as constructed according to principles of this invention, comprises a serviceable filter media that is positioned within an air-oil mixture flow passageway in the assembly housing. The serviceable filter provides improved oil separation and removal efficiency without adversely impacting separator service life.
A separator assembly of this invention, for filtering air flow and separating air-contaminate mixtures, comprises a housing having an outer wall and a channel disposed therein between a primary gas inlet and a primary gas outlet. An air filter is joined to the primary gas inlet for filtering air from the immediate environment for introduction into an engine intake system via the primary gas outlet.
The housing includes a secondary inlet port through the outer wall, for receiving an air-oil mixture taken from an engine crankcase breather, and a secondary outlet port through the channel wall, for delivering separated air for introduction into an engine intake system via the primary gas outlet. A baffle is disposed axially within the housing and extends between the outer wall and the channel wall. The baffle, outer wall, and channel wall together define first and second air flow passageways between the secondary inlet and secondary outlet ports.
A removable filter element is disposed within at least one of the first and second passageways to capture air-borne particulate matter and/or aid in the coalescence and separation of oil from the air-oil mixture. The assembly includes means for removably attaching the serviceable filter element within the housing and for providing a substantially air-tight seal with the housing.
Air filter/oil separator assemblies of this invention are capable of providing improved oil removal efficiency without adversely compromising separator service life, when compared to conventional air-filter/oil separators. Air filter/oil separator assemblies of this invention are known to provide an oil removal efficiency that is up to 20 percent greater than that provided by conventional air filter/oil separator devices that either have a permanent internal filter, or that lack an internal filter altogether.